Commit Graph

3 Commits

Author SHA1 Message Date
nmlgc 1e2c7ad37e [Reverse-engineering] [th03] Collision bitmap: Rectangles (undecompilable)
Reason: Self-modifying. -.-

The main shape used for drawing into this bitmap. "Stripes" would have
been a better name, with only the top 2 (screen) / 1 (VRAM) out of
every 8 (screen) / 4 (VRAM) pixels inside these rectangles being
actually set as collidable inside this bitmap. If a player's hitbox
happens to be smaller than 8 (screen) / 4 (VRAM) pixels, this would
mean that a player could dodge right through two of these stripes. Same
for the CPU, which would make it obvious how it could cheat.

But are player hitboxes actually small enough for that to be possible?
Gotta add another push to find out…

(Also, wow, that's some ingenious bit twiddling right there… and it's
all completely correct. 🤯 Whether all that complexity and especially
all that register overloading would have been *necessary*, on the other
hand…)

Completes P0182, funded by Lmocinemod and [Anonymous].
2022-02-18 09:36:34 +01:00
nmlgc c04ca8da91 [Reverse-engineering] [th03] Collision bitmap: Drawing slopes (undecompilable)
Reason: Self-modifying. -.-

Only used in Chiyuri's EX Attack (the one with the diagonal lasers).

Part of P0182, funded by Lmocinemod and [Anonymous].
2022-02-18 09:36:34 +01:00
nmlgc 3072208336 [Reverse-engineering] [th03] Collision bitmap: Variables and constants
Oh wow, it's exactly how I always naively imagined collision detection
to be implemented in a fixed-resolution 2D bullet hell game with small
hitboxes.

Part of P0182, funded by Lmocinemod and [Anonymous].
2022-02-18 09:36:34 +01:00